In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the so-called felsic rocks. The term roughly corresponds to the older basic rock class.

Mafic lava, before cooling, has a lower viscosity than felsic lava due to its lower silica content. Water and other volatiles can more easily and gradually escape from mafic lava, so eruptions of volcanoes made of mafic lavas are less explosively violent than felsic lava eruptions. Most mafic lava volcanoes are oceanic volcanoes, like Hawaii.